About the CM to Inches Converter
Convert centimetres to inches, or inches back to centimetres, with the exact factor and the working shown. Heights also come out in feet and inches, and every result is given to the nearest sixteenth of an inch, the marking on most tape measures and rulers.
To go the other way, press Swap and type a height in feet and inches, such as 5 ft 10 in.
How it works
Since 1959 the inch has been defined as exactly 2.54 centimetres, so this conversion has no approximation in it. Dividing by 2.54 turns centimetres into inches; multiplying by 2.54 turns inches into centimetres.
The division is done with exact decimal arithmetic rather than ordinary floating-point numbers, and the answer is rounded only once, at the end, to the number of decimal places you choose.
inches = centimetres ÷ 2.54 centimetres = inches × 2.54 feet = whole part of (inches ÷ 12), with the inches left over
Because 2.54 is exact, converting a number to inches and back gives you the number you started with, apart from the rounding you chose for display.
Assumptions and limits
- Inches are international inches (2.54 cm). The old US survey inch differed by about 2 parts per million and is no longer used for everyday measurement.
- Feet-and-inches results round the inches to 2 decimals; if that rounds up to 12, it becomes the next whole foot (182.87 cm is 6 ft 0 in, not 5 ft 12 in).
- Commas aren't accepted as decimal separators, to avoid confusing 1,5 (one and a half) with 1,500.
Worked examples
A height of 180 cm
180 ÷ 2.54 = 70.866… inches. Twelve inches make a foot, so that is 5 feet (60 inches) and 10.87 inches left over: about 5 ft 10.9 in. On a tape measure the nearest mark is 70 7/8 inches.
A 15.6-inch laptop screen
Screen sizes are measured diagonally in inches. 15.6 × 2.54 = 39.624 cm, so a 15.6-inch screen is about 39.6 cm corner to corner.
A4 paper
ISO 216 sets A4 at 210 × 297 mm, which is 21 × 29.7 cm. Dividing each by 2.54 gives 8.27 × 11.69 inches, slightly narrower and longer than US Letter (8.5 × 11 in).
Heights in centimetres, inches and feet
Rounded to 2 decimal places, halves up.
| Centimetres | Inches | Feet and inches |
|---|---|---|
| 150 cm | 59.06 in | 4 ft 11.06 in |
| 155 cm | 61.02 in | 5 ft 1.02 in |
| 160 cm | 62.99 in | 5 ft 2.99 in |
| 165 cm | 64.96 in | 5 ft 4.96 in |
| 170 cm | 66.93 in | 5 ft 6.93 in |
| 175 cm | 68.90 in | 5 ft 8.90 in |
| 180 cm | 70.87 in | 5 ft 10.87 in |
| 185 cm | 72.83 in | 6 ft 0.83 in |
| 190 cm | 74.80 in | 6 ft 2.80 in |
How to use the CM to Inches Converter
- Type the length in centimetres. Use a dot for decimals, for example 172.5.
- Read the inches. The answer updates as you type, with feet and inches and the nearest 1/16 inch underneath.
- Swap to go back. Press Swap to convert inches (or feet and inches) to centimetres.
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54. This was agreed internationally in 1959 and is how the inch is defined today, so the factor is not a rounded figure; any rounding you see is only in the final answer.
How do I convert my height from cm to feet and inches?
Divide the centimetres by 2.54 to get inches, then divide by 12: the whole number is the feet and the remainder is the inches. The calculator does both steps and shows 180 cm as 5 ft 10.87 in.
What does 'nearest 1/16 inch' mean?
Rulers and tape measures in inches are usually marked in sixteenths. The calculator rounds to the nearest sixteenth and simplifies the fraction, so 70.866 inches is shown as 70 7/8, the mark you would actually read.
Why does another site show a slightly different number?
Some converters use a rounded factor such as 0.3937 inches per centimetre. It is very close, so everyday lengths match, but it drifts on long ones: for 10,000 cm it gives 3,937.00 inches, while the exact answer is 3,937.01. Check which factor a site uses if the last digit matters.
Can I enter inches with a fraction, like 5 1/2?
Not yet: type the decimal (5.5) instead. Common fractions are 1/4 = 0.25, 1/2 = 0.5 and 3/4 = 0.75, and 1/8 = 0.125 if you need finer steps.
Sources
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